This invention relates to chromatography. In particular this invention relates to the high performance liquid chromatographic separation of a liquid hydrocarbon mixture into three components, namely acyclic paraffins, naphthenes and total unsaturates.
Liquid chromatography has been employed to characterize the group composition of crude oils and petroleum products since the beginning of this century. The fluorescent indicator absorption (FIA) method, ASTM D 1319, has served for over 30 years as the official method of the petroleum industry for measuring the paraffinic, olefinic, and aromatic content of gasolines and jet fuels.
High performance liquid chromatography (HPLC) offers many advantages over open column chromatography, not the least of which is speed. However, a severe shortcoming of most HPLC approaches to a hydrocarbon group-type analysis is the difficulty in obtaining accurate response factors applicable to different distillate products. Accuracy is generally compromised when these response factors are used to analyze hydrotreated and hydrocracked materials. Given significant changes in the hydrocarbon distribution within a certain group-type, analytical results will be misleading for such samples because of the variation in response exhibited by most routinely used HPLC detectors.
It is an object of the present invention to provide an analytical method whereby the acyclic paraffins, cycloparaffins and unsaturates, i.e., aromatics plus olefins, in a solution consisting of many kinds of hydrocarbon compounds can be easily and quickly analyzed with high reproducibility and accuracy.
Other objects and advantages of the present invention will be apparent to those skilled in the art.